Drying arrangement such as a tunnel



Feb. 28, 1956 c. D. MUYDERMAN 2,736,108

DRYING ARRANGEMENT SUCH AS A rLUNNEL. KILN WITH TRANSVERSE CIRCULATION Filed April 18, 1951 JNVENToR. coERT DANIEL MUYDERMAN ATTORNEY DRYING ARRANGEMENT SUCHS AiTUNNEL KILN WITH TRANSVERSE CIRCULATION Coert D. Muyderman, Utrecht, Netherlands, assignor to Nederlandse Organisatie voor Toegepast-Natuurwetenshappeliik Onderzoek ten behoeve van Nijverheid, Handel en Verkeer, The Hague, Netherlands, a corporation of the Netherlands v v 2 Application April 1s, 1951, ser-iai No. 221,565 Claims priority, application Netherlands April 27,` 1950 6 Claims. (Cl.

This invention relates to a drier such -as a tunnel kiln with transverse circulation, consisting of a'drying chamber and a room for the circulation of the drying medium such as air or other suitable gas by which the drying medium is passed over heating elements and this medium -is distributed over the drying chamber as'uniformly as possible.

A drying arrangement is known with transverse circulation in which the drying air is passed overheating elements placed in its passage and is conveyed past sloping bafes, before (and after) the drying chamber, the drying medium thus being distributed uniformly over the drying chamber and the side walls of this drying chamber being constructed of a material through which the drying medium can pass easily. This material may be a fabric with wide meshes or perforated plates. L

Further a drying arrangement is known which, except the drying chamber itself, is divided into compartments by transversely arranged vertical partitions by which the transverse circulation is under better control. The heating elements may be heated by for instance steam or ue gases.

Also a tunnel kiln is known without transverse circu lation in which the lower surface of the bottom of the drying chamber is heated by hot flue gases, which gases can enter in a controllable way under the bottom of the drying chamber by several openings provided with dampers longitudinally distributed over the length of the drying chamber; this tunnel kiln contains no sloping batlies as no transverse circulation takes place.

Heating elements arranged in the passage of the circulating drying medium in tunnel kilns with transverse circulation cause a relatively great resistance, and further when ue gases are applied these elements, having mostly a narrow passage for these liue gases, will be fouled quickly and are difcult to be cleaned.

The kiln with transverse circulation according to the invention comprises a drying chamber adapted for receiving therein the articles to be dried, a circulation chamber surrounding said drying chamber for transversely passing the drying medium into and from the dry ing room, said circulation chamber being provided with sloping baflies for conveying the drying medium smoothly and uniformly to said drying chamber and discharging said medium uniformly and smoothly from the drying chamber, said baffles also forming heating elements for ICC a supply of fresh drying medium, for instance at the end of the tunnel and removing used drying medium at the lirst part of the tunnel. If required and depending on the material to be dried and the condition of this material,

a portion of passing drying medium may be withdrawn at a selected point of the tunnel kiln and re-cycled into the feed of fresh drying medium at the end of the drying kiln.

The accompanying drawing illustrates a now preferred embodiment of a tunnel kiln according to the invention. Figure 1 is a vertical cross section of this tunnel kiln. Figure 2 is a vertical longitudinal section of this tunnel kiln, and

Figure 3 is a perspective view of one of the baffles of the kiln. The kiln, as shown in the igures, comprises a drying chamber 1 through which are passed the products to be dried, such as bricks, for instance in piles or on racks or conveying carriages 2. The side walls of the drying chambers may consist of the perforated plates 3 and 4. The blowers 9 direct the drying air along slanted and corrugated bailies 5 and 6, thus distributing the dry ing air uniformly over the drying chamber. The space for the drying air, except the drying chamber itself, is divided in compartments by the transversely arranged vertical partitions 11 and 12, eiecting a transverse circulation of the air. The disposition of the partitions is clearly shown in Fig. 2.

Bailies 5 and 6 together with the wall of an outer housing 29 form spaces 7 and 8 heating gases through which, for instance iiue gases, are conducted by which the bailles are heated so that they transmit their heat to the drying air. These flue gases are supplied to the spaces 7 and 8 from channels 20 and 21 through openings 27 and 28 distributed longitudinally over the tunnel kiln and fitted with dampers 22 and 23 by which the heating of the drying air can be controlled. This may be of advantage for instance when the temperature of the ue gases is the drying medium and which may be electrically heated y lower than the starting temperature of the drying air owing longitudinally through the kiln; in this case the flue gases are introduced at a distant point.

The iiue gas spaces 7 and 8 can easily be cleaned by cleaning openings 24 and 25 provided with closing members. The flue gases are discharged through a channel 26.

A blower 14 feeds heated drying air from a channel 17 to the tunnel kiln for instance at one end of the tunnel. Recycled air can be directed by a blower 18 from a selected point, dependent on the products to be dried and their conditions, to channel 17 through conduit pipes 15 and 16, disposed in the liue gas spaces 7 and 8. The used drying air is discharged by the discharge blower 19 at the other end of the tunnel. The recycled air is reheated in the conduits 15 and 16 as this air, being withdrawn from the first parts of the tunnel, has mostly a low temperature.

What is claimed is:

l. A kiln for drying stock, comprising an elongated housing including transverse and longitudinal partition walls dividing the space Within the housing in a longitudinal outer chamber transversely sub-divided in a plurality v of compartments and a longitudinal inner chamber disposed within the outer chamber extending along the length of the housing and separated from the outer chamber by side walls and a top wall formed by the respective ones of said partition walls, the said inner chamber constituting a drying space for the stock to be dried, the side walls being formed with transverse passage openings connecting the inner chamber with said compartments, pairs of gas impervious deliectors, the deectors of each pair being disposed in one of said compartments adjacent to opposite side walls of the inner chamber and slanted outwardly from the base of the respective side wall, toward the juxtaposed housing wall to partition each of said cornpartments in an upper part and two lower parts, the latter being situated on `opposite sides of the drying chamber, the upper part of each compartment forming a circulation path transverse to the housing and including the respective juxtaposed section of the inner chamber, blower means in the upper part of each compartment for circulating a gaseous drying fluid through said transverse circulation paths, the said passage openings and the said deflectors has traversed all the upper compartment parts intermediate of the inlet and the outlet compartment part respectively and the inner chamber, and reflux conduit means connecting the outlet conduit means with the inlet conduit means for rcfluxing discharged drying fluid through the housing.

2. A kiln according to claim l, wherein the said deectors comprise gas impervious plates corrugated in vertical direction.

3. A kiln according to claim 1, wherein a duct for lhot gaseous fluid extends beneath all the lower parts of the compartments on each longitudinal side of said inner chamber, each of said ducts including a plurality of branch ducts each communicating with one of the lower compartment parts for heating the said compartment parts and the deilcctors.

4. A l-:iln according to claim3, wherein the said reflux conduit means are disposed within said lower compartment parts for heating the Huid reuxed through the said conduit means.

5. A kiln according to claim -4 and further comprising adjustable control means fitted in said branch ducts for controlling the flow of heating fluid through said branch ducts into the lower compartment parts.

6. A kiln for drying stock, comprising an elongated lll housing including partition. walls dividing the space within the housing in a longitudinal outer chamber and a longitudinal inner chamber disposed within the outer chamber and separated therefrom by side walls and a top wall formed by said partition swalls, 4the said inner chamber constituting a drying .space for the stock to be dried, the said side walls being formed with transverse passage openings connecting the inner chamber with the outer chamber, gas impervious deectors disposed in the outer chamber adjacentl tothe opposite side lwalls of the inner chamber and slanted, outwardly from the base end of the respective side wall toward the juxtaposed housing wall to partition the outer chamber in an upper part and two lower parts, said lower parts being .situated on opposite sides of the inner chamber, the upper part of the outer chamber forming circulation paths transverse to the housing andy including the inner chamber, blower means in the upper part of the outer chamber for circulating a gaseous drying fluid through said-transverse .circulation paths, the said passage .openingsand the said deflectors effecting a substantially uniform distribution of the transverse fluid flow through the yinner chamber, inlet conduit means communiclating vwith Athe upper part of the outer chamber near one end of. the housing for feeding a gaseous drying fluid into said outer chamber-,outlet conduit means communieating withv the outerchamber near the other end of the housing for discharging the drying liuid from the outer chamber, yand reux conduit means disposed within the housing and. connecting the loutlet conduit means with the inlet conduit means for refluxing drying fluid discharged from .the outer chamber through the housing.

References Cited inthe fleof this patent UNITED STATES PATENTS France Ian. 10, 1946 

